Device for changing the spring rate of a vehicle suspension system



Sept. 17, 1963 B. WALKER DEVICE FOR CHANGING THE SPRING RATE 0F AVEHICLE SUSPENSION SYSTEM 2 Sheets-Sheet l Filed May 12, 19Go Sept. 17,1963 B. WALKER r DEVICE FOR CHANGING THE SPRING RATE OF' A VEHICLESUSPENSION SYSTEM 2 Sheets-Sheet 2 Filedv Maly` 12, 1960 mw ww Dm. 19mm.

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United States Patent Oiice 3,104,118 Patented Sept. 17, 1363 3,104,118DEVICE FOR CHANGING THE SPRING RATE GF A VEHICLE SUSPENSION SYSTEMBrooks Walker, 1280 Columbus Ave., San Francisco 11, Calif. Filed May12, 1960, Ser. No. 23,7110 Claims. (Cl. 28o-124) This invention pertainsto improvement in vehicle suspension systems and particularly to meansfor varying the support of the rear of the vehicle. This inraccomplished by means that transfer the vertical motion of the rearaxle to horizontal motion by the use of bell cranks and cables andresist such horizontal motion by the cornpression of a single pneumaticiiexible device, such as a tire of smaller diameter than the diameter ofthe rear tires lof the vehicle.

Another obje-ct is to load and unload such an auxiliary support by ahydraulic or pneumatically operated cylinder acting on said cables.

Another object is to actuate such a device with the power 4available tooperate the power steering thnough a leveling valve of conventionaldesign.

Another object is to locate the controls near the pump and powersteering.

Another object is to operate the resilient means by la remote controlfrom the motion lof the rear axle or bell crank to eilect leveling yandprevent continuous circulation of power steering lluid from the pump tothe rear of the vehicle to the normal location of a self-leveling valve.

Another object is to keep the hydraulic control for leveling wellforward of the rear tires to reduce the piping from the engine power-source and thereby reduce the cost.

Another object is to provide `a visual indicator of the rear axlemotion, available in the drivers compartment, so that the driver canjudge the auxiliary support needed in case a manual override control isdesired in order -to get higher frame to ground clearance, or a irmerride is desired.

Another object is to reduce the action of the auxiliary yieldable meansrelative to the motion of the rear axle with respect to the vehicleframe. By this construction the approximate inches plus or minus of axletravel is reduced to about one-half that much. This reduced actionresults in a better ratio for the compressibility of the auxiliary tire.lf the rear springs of a vehicle have a rate oi about 115 lbs. per incheach which might be about right for a light load of only the driver ordriver and one passenger; for eight passengers in a station wagon withluggage 200 lbs. per inch might be a desirable rate.

Another object is to have an extra shock Iabsorber connected to theaction oi the auxiliary support to change the shock resistance when theauxiliary support is fully Iactive as compared to the shock absorbedaction when the auxiliary support is inactive.

Other objects will be more particular-ly pointed lout in theaccompanying specification land claims.

Further objects, features and advantages of thisinvention will becomeapparent from a consideration of the following description, the appendedclaims and the accompanying drawing in which:

FlG. 1 is a plan view partly cut away showing one form of thisinvention.

FIG. 2 is a longitudinal sectional view looking along the line 2-2 inFIG. l;

FIG. 3 is a reduced schematic side view showing the plumbing and heightcontrol;

FIG. 4 is a fragmentary plan view showing an alternative mounting forthe hydraulic cylinder and cable actuating pulley in this invention.

In all gures like numerals of reference refer to cor; responding parts.

In FIGS. 1-3 I have. shown a vehicle having .a fname 10, rear axle S,rear tires 5, rear springs 9 for supporting a light load and auxiliarysupport tire 20 connected to the rear axle by arm 17, cables 35 and 36,bell cranks 12 and 13, tie rods 14 which connect the rear arm of bellcranks 12 and `13 to the rear axle 8. Bell cranks 12 and 13 are pivotedon axles 12a and 13a, respectively, and axles 12a and 13a are supportedin bearings 12b and 13b, respectively, which are each suitably securedtothe vehicle frame 10. Cables 35 and 36 are pivoted to bell cranks 12and 13, respectively, by means of clevices 35a and pins 35h. Cable 36 is`attached to bell crank 13 by clevice 35a and pin 35b.

The arm 17 is pivoted adjacent one end to the trame 10 by means of a pin17C. At its ends the arm 17 carries pulleys 18 and 18a supported on pinsyltib, and pulleys 19 and 19a which are piuoted to .arm 17 by pins l19b.Cable 35 is trained about pulleys 19 and 19a, and cable 36 is trainedabout cables 18 and 18a. In addition, the cable 36 is trained about apulley 33 and connected by a clamp 29 to cable 35. If desired, thecables 3S and 36 mlay take the form of a single continuous cable.

The rear axle 8 is also connected to `frame 10 by shock absorbers 6; anauxiliary shock absorber 6a is connected between a bracket 16d on :frame10 and an extension 17a for arm 17 to provide auxiliary snubbing whenauxiliary support is being provided through Iauxiliary support tire 20.

A hydraulic control cylinder 30 is pivoted to a bracket 10c on frame 10by a pin 36a. Clyinder 30 has apiston rod 3ft provided with a forked endwhich supports a pin 36a which rotatably supports the pulley 33. Pulley33 pulljlls `on cables 3S and 36 which can be one continuous ca e.

Auxiliary tire 2@ has a wheel 20a Iand axle 2,1 which is supported by abracket 11 which is bolted to cross frame 10a at its front end and tobracket 10c at its rear end and has slot 11a for 'supporting axle 21 andstill allow fore and aft action of axle 21 when tire 20 is compressedbetween curved heel 17!) of arm 17 .and curved shoe 25. Shoe 25 lissupported on threaded stem 26 and adjusted fore land aft by nuts 2.7 and27a on each side of the brackety 10c through which stem 26 passes. Thecontrol for cylinder 30 and piston rod 34 which changes the load carriedby cables 35 and 36 through the varying compression of auxiliary tire 20is shown schematically in FIG. 3. Engine 6K6 which drives the vehiclethrough drive shaft 7k drives power steering pump 60 through pulley 64,belt 63 and pump pulley 62. Reservoir 61 is mounted on pump 60 which hasthe usual connections and flow control valves common to current practicebut not shown as it forms no part of this invention.

Height control valve 80 is connected to pump 60 by pressure line 68.Line 69 carries pressure to power steering unit 65 either in the opencenter position or when the piston rod 34 is moving in either direction.

Line 70 returns liquid from power steering unit 65 to reservoir 61. Line31 goes to the front end of cylinder 30 from valve 80 to cause pistonrod 34 to be retracted to increase the auxiliary support throughcompression of auxiliary tire 2t). Line 32 goes to the rear of cylinder30 and connects the closed end of cylinder 30 to reservoir 61.

The operation of valve 80 may be similar to the valve shown in PatentNo. 2,940,476, entitled Open Center Four Way Valve, assigned in full toapplicant, or it may be any other type of suitable height control orleveling valve. The valve 80 is actuated mechanically by a link 72 whichextends from the valve 80 to the operators compartment. The advantage oftransmitting the motion of the axle forward to a valve near the pumpreduces the length of tubings and reduces the cost accordingly. The costof transmitting the axle motion forward by wire cable or rod is muchless than carrying one or more high pressure tubes back to or near therear axle.

The rear axle motion and position is transmitted to the driverscompartment by means of cable 41 through conduit 40 to indicator ball 45operating in housing 46 and visible through slot 47. Coil spring 4Spresses against indicator ball 45 and is connected at its upper end tocable 41 to keep control cable 41 in tension at all times. The height ofball 45 indicates the axle 8 motion relative to frame 1i? in reducedratio. The position of ball 45 in slot 47 also indicates the amount offrame lift in case of override control of the auxiliary suspensionsystem.

In FIGURE 4, the hydraulic cylinder assembly 30 is illustrated mountedon the pin 39a carried by the frame bracket e at la position forwardlyof the transverse frame member 10a. In this installation, the cables 315and 36 are trained about the opposite sides of the pulleys 18a and 19afrom that illustrated in FIGURE l. In the FIGURE 4 installation, whenthe cylinder assembly 30 is operated to retract the piston rod 34, thearm 117 is swung in a clockwise direction to compress tire 2G as viewedin vFIGURE 1. The advantage of the FIG- URE 4 installation is that thelengths of the lines 31 and 32 are reduced.

In the operation of the system of this invention, when the rear end ofthe vehicle is to be elevated, or when the resistance of the springs 9to up and down movement of frame 10 is to be increased, such as when anunusually heavy load is to be carried in the vehicle, the piston rod 34is retracted `to swing the arm `17 in a clockwise direction to compressthe tire Z0, which constitutes a compressible chamber or yieldablemeans, between the shoe 25 and the heel V17b of arm 17. The increasedtension in cables 35 and 36 provides for a rotation of the bell cranks12 and 13 in a direction to move the tie rods 14 downwardly to increasethe bow of the springs 9 and elevate the rear end of the vehicle frame10 and increase the combined resistance of the springs 9 and tire 20 toup and down movement of frame 10. The extent of upward movement of therear end of the vehicle A10 relative to the rear axle 8 is indicated bythe location of the ball 45 which is visible in the operatorscompartment.

During operation of the vehicle, any flattening out of the leaf springs9 is yieldably resisted by the resistance of the tire 20 to furthercompression and the resistance of the tire 20 to compression maintainsthe cables 35 and 36 taut. As a result, the tire 20 functions to providean auxiliary pneumatic suspension for the rear end of the vehicle.Whenever a lirmer ride is desired for the Vehicle, the hydrauliccylinder assembly 30 can be actuated to increase the bow of the springs9 and the resistance of the tire 2? to further compression. By varyingthe contours of the heel 17b and the shoe 25, the' degree of resistanceof tire 20 to travel of lever 17 may be varied to provide the desiredauxiliary suspension or support.

It will be understood that the specific construction of the improvedvehicle suspension system which are herein disclosed and described ispresented for purposes of explanation and illustration and is notintended to indicate limits of the invention, the scope of which isdefined by the following claims.

What is claimed is:

l. In a vehicle having a frame with spaced side rail elements, a pair ofroad wheels at the front and at the rear of the frame, wheel supportingmeans, spring means interconnecting said frame and wheel supportingmeans, a pair of bell cranks having the center and one arm pivoted tothe frame and the rear wheel supporting means respectively, a leverpivoted at one end to one said rail element and at the opposite end tothe opposite said rail element through a shock absorber, a pair ofcables, one cable having one end connected to the second arm of one saidbell crank, the other cable connected to the second arm of the othersaid bell crank, a pair of pulleys at opposite ends of said lever, saidcables extending through each said pair of pulleys, a supporting memberon said frame, resilient means engaging the lever between said pulleysand engaging said supporting member, and a ram connected to the frameand to the other ends of the cables for drawing the lever against saidresilient means which supports a portion of the vehicle load.

2. In a vehicle having a frame, a pair of road wheels at Ithe front endand at the rear end of the frame, wheel supporting means, spring meansinterconnecting said frame and vwheel supporting means, a pair of bellcranks having the juncture between the ends pivoted to the frame and onearm pivoted to the rear wheel supporting means, a lever pivoted at oneend to one side of the frame, a tirst pair of pulleys on the oppositeend of the lever, a second pair of pulleys on the lever adjacent to thepivot thereof, a pair of cables, one connected to the second arm of eachsaid bell crank, said cables passing through said pairs of pulleys, asupport member on said frame, resilient means acting against a portionof said lever located between said pair of pulleys and said supportmember for supporting a portion of the vehicle load on said frame, andmeans on said frame secured to the other ends of said cables for varyingthe force thereon and the pressure on said resilient means between saidlever and support member.

3. In a vehicle having a frame, a pair of road wheels at the front andat the rear of the frame, wheel supporting means, spring meansinterconnecting said frame and wheel supporting means, a pair of bellcranks having the center and one arm pivoted to the frame and the rearWheel supporting means respectively, a lever pivoted at one end to theframe and at the opposite end to the frame through a shock absorber, apair of pulleys on said lever adjacent to the shock absorber, a secondpair of pulleys adjacent to the lever pivot, a pair of cables having oneend connected to the second -arm of said bell cranks and extended overboth pairs of pulleys, a supporting member on said frame, resilientmeans engaging said member and said lever between said pairs of pulleys,said resilient means Vsupporting a portion of the vehicle load on saidframe when' a force is applied thereto by the lever, and :a ramconnected to the other ends of said cables for applying a iforce to thelever and to said resilient means, said ram extending forwardly o-f saidlever and secured to the forward portion of said frame.

4. In an auxiliary support for the rear end of a vehicle having achassis frame and rear wheel supporting means which are interconnectedby spring means, a pair of bell cranks `also interconnecting the rearwheel supporting means and said chassis frame with a free arm extendingtherefrom, a lever having one end pivoted yto one side of the chassisframe and the opposite end connected to a 6 hydraulic shock absorberconnected to the other side of 5. An auxiliary support as recited inclaim 4, wherein said chassis iframe, `a pair `of cables having one endconsaid backup member and lever engage said tire with opponected to thefree arm of the bell cranks and passing sitely presenting concavedKareas for increasing the pres- 'hmllgh :a Pair 0f Pulleys disposed at'a medial P'OI'EOH Of sure rate of the tire as lthe load thereonincreases. said lever yand rthrough a pair of pulleys on the lever near5 the pivot thereof, -a backup member fixed to said frame ReferencesCited in the iile of this patent and spaced `from said lever, aninflatable pneumatic tire UNITED STATES PATENTS engaging said leverbetween said pairs of pulleys, and

2,825,580 Walker Mar. 4, 1958 abutting said member, iand Ia ramconnected `te the other ends of said cables for applying a load theretoand to 10 2,872,209 Walker Feb. 3, 1959 said lever which is transferredto the tire. 2,893,505 Schultz July 7, 1959

2. IN A VEHICLE HAVING A FRAME, A PAIR OF ROAD WHEELS AT THE FRONT ENDAND AT THE REAR END OF THE FRAME, WHEEL SUPPORTING MEANS, SPRING MEANSINTERCONNECTING SAID FRAME AND WHEEL SUPPORTING MEANS, A PAIR OF BELLCRANKS HAVING THE JUNCTURE BETWEEN THE ENDS PIVOTED TO THE FRAME AND ONEARM PIVOTED TO THE REAR WHEEL SUPPORTING MEANS, A LEVER PIVOTED AT ONEEND TO ONE SIDE OF THE FRAME, A FIRST PAIR OF PULLEYS ON THE OPPOSITEEND OF THE LEVER, A SECOND PAIR OF PULLEYS ON THE LEVER ADJACENT TO THEPIVOT THEREOF, A PAIR OF CABLES, ONE CONNECTED TO THE SECOND ARM OF EACHSAID BELL CRANK, SAID CABLES PASSING THROUGH SAID PAIRS OF PULLEYS, ASUPPORT MEMBER ON SAID FRAME, RESILIENT MEANS ACTING AGAINST A PORTIONOF SAID LEVER LOCATED BETWEEN SAID PAIR OF PULLEYS AND SAID SUPPORTMEMBER FOR SUPPORTING A PORTION OF THE VEHICLE LOAD ON SAID FRAME, ANDMEANS ON SAID FRAME SECURED TO THE OTHER ENDS OF SAID CABLES FOR VARYINGTHE FORCE THEREON AND THE PRESSURE ON SAID RESILIENT MEANS BETWEEN SAIDLEVER AND SUPPORT MEMBER.